The invention relates to preservation methods for aquatic animals developed as techniques for preserving the freshness of aquatic animals including fish, crustaceans such as prawns and crabs, and cephalopods such as squids and octopuses when such animals are to be transported in live form mainly for distribution as food.
Capturing and delivering to the consumer aquatic animals including fish, crustaceans such as prawns and crabs, and cephalopods such as squids and octopuses in a live state allows for high pricing of the merchandise. This being the case, significant effort has been exerted in this field.
Fish, cephalopods, and other such aquatic animals are generally transported in a vehicle equipped with a preservation tank. A widely used method for transporting crustaceans involves packing them in sawdust.
However, it is clear that forcing animals that live in the wide ocean into a confined environment for transport has a negative physical effect. There are limits to the transport as wellxe2x80x94the types, sizes, and numbers of transportable animals are limited. Furthermore, transport via a preservation tank, which requires a special vehicle, is expensive. This form of transport presents many issues requiring addressing, such as physical damage to the animals from bumping or fighting within the tank and weakening due to the poor conditions. As well, the animals face many risks before being delivered to the consumer.
A large problem facing live cephalopods transported in sawdust is weight loss, so this means is suited only for very short-term transport.
Therefore, animals that could not be transported using the above methods, or those requiring long-term transport, had to be frozen or processed where they are caught.
Various research studies are being conducted to eliminate these transport-related problems.
There is a need for a method for transporting fish and similar animals in a live state that prevents deterioration during shipping, enables the animals to withstand long-term shipping, and is suited to high-volume transport. Such a method would reduce or suppress the motor functions of the live fish and preserve them in a confined area while adequately maintaining their respiratory systems and other life support functions.
Methods disclosed in Japanese Unexamined Patent Application Publications (Kokai) H7-16037 and H7-50956 relate to cutting or damaging the spinal cord or cranial region of live fish with an implement that is heated to a high temperature or electrically charged in order to slow motor functions.
But the spinal cord is a large neural bundle that plays an essential life support role in vertebrates. A seriously damaged cord may lead to a quick death. In the above-mentioned prior art, treatment is conducted with a heated or electrically charged surgical implement in order to stop the flow of blood and prevent infection. But metal chopsticks and saws, examples of these implements, may cause more than the minimum necessary damage, and dedicated training is required to perform the task properly. Externally locating the spinal cord of a fish is particularly difficult. If the proper spot is missed and the fish is consequently probed repeatedly, it will become extremely weak and not be able to withstand long-term preservation.
This method is not suitable for the horse mackerel and other small fish.
Treating the sides of fish with the above implements causes external scarring, which notably lowers the price when the fish are to be served live.
Examples of conventional methods to control motor functions are a technique that uses low temperatures and one that applies an electrical shock. But no method that can fulfill the needs of distribution has yet been developed.
The inventor believes the major cause of these problems to be a lack of adequately preparing the physiology of the animals for the rigors of distribution. His earnest research has led to the invention of preservation methods for aquatic animals that, according to the variety of aquatic animal caught, suppress the motor functions of the animal in a manner suited to its physiology and preserve the animal in a way that allows it to fully withstand shipping.
The invention establishes treatments that temporarily or semi-permanently suppress the motor functions of aquatic animals and preserve the animals at or below their minimum survival temperature or in disinfected water. Therefore, aquatic animals survive motionless even in a small container, and such small containers may be used for transport via truck, so large amounts of aquatic animals can be maintained in a state of excellent vitality and delivered to the consumer at a low shipping cost. Not only do the animals remain immobile, but the methods lack the danger present in processing under the above-mentioned prior art. The problems of injury to the organisms and weight loss are thus solved outright.